Simple Trichomes Research Articles

EVALUATION OF RELATIONSHIPS WITHIN ERIODICTYON (HYDROPHYLLACEAE) USING TRICHOME CHARACTERISTICS

All 13 taxa of Eriodictyon Bentham (Hydrophyllaceae) were examined to determine the range of variation in trichome characters within the genus. Four simple trichome types were found: short and straight, intermediate length and straight, long and straight, long and wavy. Glandular capitate trichomes were also found in some species. Sessile glands were also observed but not included in the study. Most taxa displayed unique combinations of trichome types on stems, leaves, inflorescence axes and flower parts that allowed those taxa to be identified using trichome types alone. Trichome data support most previous taxonomic treatments, but suggest that 1) the two varieties of E. traskiae are extremely similar, 2) the rare E. altissimum is most similar to the widespread E. californicum, 3) the rare E. capitatum is allied with E. crassifolium var. nigrescens or perhaps E. angustifolium, 4) E. crassifolium var. denudatum and E. crassifolium var. nigrescens are essentially indistinguishable using trichome characters and, coupled with variation in other characters, are best combined under the name E. crassifolium var. nigrescens. Trichome characters provide a wealth of taxonomically useful information and may prove useful in the study of related genera of Hydrophyllaceae.

Bacterial leaf symbiosis in Dioscorea sansibarensis: morphology and ultrastructure of the acuminate leaf glands*

Abstract The symbiosis between a bacterium and the West African rain forest yam Dioscorea sansibarensis is described for the first time at the ultrastructural level. The bacteria are harboured in glands which run the entire length of the pronounced ‘drip‐tip’ leaf acumenae of the host plant. Each acumen, which may be up to 12 cm long in very large mature leaves, contains from two to six bacterial glands. The glands are kidney‐shaped in cross section and contain numerous multicellular simple trichomes which arise from the epidermis of the gland floor and project into the lumen of the gland. The bacteria are Gram‐negative and variously rod, ovoid, and coccoid in shape. The bacterial cells contain mesosomes, polyhydroxybutyrate granules and large electron‐dense bodies. Bacteria‐free plants grow more slowly and produce one yellowish‐green leaf per node in contrast to the vigorous growth habit of infected plants, with two deep green leaves per node. Infected plants exposed to a variety of atmospheres containing acetylene, both in the light and in the dark, failed to reduce acetylene to ethylene, indicating that nitrogen fixation is not a function of this symbiosis.

Three New Species of Solanum Section Geminata (G. Don) Walp. (Solanaceae) from Panama and Western Colombia

Three New Species of Solanum Section Geminata (G. Don) Walp. (Solanaceae) from Panama and Western Colombia

New Neotropical Species of Meliosma (Sabiaceae)

New Neotropical Species of Meliosma (Sabiaceae)

Resistance to Spotted Alfalfa Aphid (Homoptera: Aphididae) in Alfalfa Seedlings of Two Plant Introductions

Temporary resistance to Therioaphis maculate (Buckton) occurred in young seedlings of two alfalfa plant introductions (PI 406295 and PI 406296). Although this resistance was not manifested in no-choice tests with mature plants or under prolonged aphid attack in free-choice tests with seedlings, it was heritable. The cause of this resistance appeared to be a dense covering of simple trichomes on the seedling stems.

Leaf anatomy of Gluta (L.) Ding Hou (Anacardiaceae)

An anatomical study of the leaves of 21 species ofGluta (L.) Ding Hou (Anacardiaceae) reveals two major groups of species which reflect the original groups of Gluta L. and Melanorrhoea Wall., and a smaller group showing intermediate, or an admixture of, characters. The anatomical characters found to be of most use in this respect are: stomatal outline in surface view; stomatal density; glandular trichomes present/absent; glandular trichome body raised/sunken; cuticle striate/not striate; midrib dimensions as seen in transverse section; kind of simple trichomes (trichome-types 1–4); epidermal cell anticlinal wall undulation and whether visible or not on cuticular surface; resin ducts present/absent in medullary parenchyma of midrib. These characters have been used in a key to the species. Some evidence is given that the lacquer covering the leaf surface of some species is produced by the terminal cells of the glandular trichomes.

Resistance of Ivy Geraniums to the Twospotted Spider Mite1

Abstract Resistance to the twospotted spider mite (Tetranychus urticae Koch) of 18 cultivars of ivy geranium [Pelargonium peltatum (L.) L’Her ex Ait.] was evaluated under greenhouse conditions by mass screening, by measuring fecundity on isolated leaves, and by paired leaf tests for selected cultivars. ‘Sybil Holmes’, ‘Yale’, and ‘Cornell’ were among the most susceptible, whereas ‘Double Lilac White’, ‘Sunset’, and ‘Salmon Queen’ were relatively mite-free. ‘Madeline Crozy’ and ‘Cornell’ were preferred for oviposition over the resistant ‘Double Lilac White’. Mite resistance was not related to density of simple or glandular leaf trichomes, but there was an apparent relationship between mite susceptibility and severity of oedema.

Studies in Bignoniaceae 31: New Species and Combinations from Amazonian Peru and Brazil

Studies in Bignoniaceae 31: New Species and Combinations from Amazonian Peru and Brazil

Leaf anatomy of Cunoniaceae

A study of leaf anatomy of 24 genera of Cunoniaceae was made. The prevailing petiole vasculature is a nearly complete, usually adaxially flattened, medullated cylinder with the flat dorsal segment separated from the ventral arc. Medullary and cortical vasculation in Codia, Cunonia, Geissois and Pancheria is correlated with an increase in leaf coriaceousness. Very few characters are uniformly found in leaves of all species; these are druse or prismatic crystals, bifacial mesophyll and unicellular and simple trichomes. In most species vein sheathing occurs. Characters of the lamina that show variation and are useful in generic delimitation are: trichome type, presence of a hypodermis, occurrence of mucilaginous cells, presence of specialized terminal veinlet cells, major and higher order venation patterns, vein sheathing type, and mature stomatal types. Stomata are of the anomocytic, paracytic or anisocytic types. Leaves of various cunoniaceous species of xerophytic environments exhibit a leathery texture, thicker cuticle, more intensive sclerification along the veins, a sclerified hypodermis, and an increase in the amount of vascular tissue per unit area. Leaf anatomy does not provide immediate clues toward elucidating the relationships of cunoniaceous genera.

The micromorphological and anatomical properties of <i>Onosma angustissimum</i> Hausskn. & Bornm. and <i>O. cassium</i> Boiss. (Boraginaceae)

The micromorphological and anatomical properties of Onosma angustissimum Hausskn. & Bornm. and O. cassium Boiss. were investigated. O. angustissimum is an endemic species. All examined taxa had secondary root structure. Crystals were seen in the stem and leaves of two species. Epidermal cells containing crystal needles were observed in O. cassium. Studied Onosma species had isobilateral type of leaves. Stomata were anisocytic and anomocytic. Glandular and eglandular trichomes especially porrect-stellate and simple trichomes were densely seen on the both upper and lower epidermis of leaves in two species. Stomata index was different in O. cassium from O. angustissimum.Keywords: Boraginaceae; Onosma; Morphology; Anatomy; LM; SEMDOI: 10.3329/bjpt.v17i1.5386Bangladesh J. Plant Taxon. 17(1): 1-8, 2010 (June)